An island of ice[2] more than four times the size of Manhattan broke off from a glacier in Greenland during the first week of August 2010. It’s drifting across the Arctic Ocean as you read this, probably headed to Canada’s east coast.

No one has to tell me that this year is shaping up to be one of the hottest on record[3] — if not the hottest. In southern Wisconsin where I live, the last time the high temperature for the day was less than 70 F was June 14 (when it was 69 F). It feels as if Wisconsin’s weather has suddenly shifted to that typical of Arkansas, a prediction made by climatologists several years ago.

Also in the first week of August 2010 the term “global warming” celebrated its 35th birthday. On August 8, 1975, Wallace Broecker published a paper titledClimate Change: Are We on the Brink of a Pronounced Global Warming?[4]in the journal Science.[5] It’s the first use of the term in scientific literature, according to a search of a database containing more than 10,000 articles.

In the three-and-a-half decades since Broecker’s paper was published, the majority of the public has gone from believing that human activities are causing the planet to warm[6] at an unprecedented rate (thanks in large part to Al Gore and his book and film titled An Inconvenient Truth[7]) back to — just recently — skeptics. Why should that be, especially during what could turn out to be the hottest summer in recorded history? It’s because of some computer hackers.

Same as it ever was

When it comes to key discoveries in the natural world, it seems there will always be initial vociferous skeptics. For example, in 1610 when Galileo[8] had the audacity to publish a paper that argued in favor of Nicolaus Copernicus’s[9] theory that the Sun, not the Earth, was at the center of the universe, the Roman Catholic Church strongly urged him to recant his belief. Galileo refused, and in 1633 the Inquisition[10] convicted him of heresy. He received a sentence of life imprisonment, although he was allowed to serve it under house arrest.

In 1962 when Rachel Carson[11] tried to warn us in her now famous book Silent Spring[12]that DDT was harming birdlife, she was attacked as an alarmist by chemical industry representatives, DDT manufacturers, and even some in the government. They relentlessly hounded her until her death in 1964.

The Copenhagen controversy

We shouldn’t be surprised, then, that just days before the United Nations Climate Change Conference in Copenhagen in December 2009, an incident dubbed “Climategate” unfolded. Unidentified persons hacked into a computer server[13] at Britain’s University of East Anglia’s Climatic Research Unit[14] and stole tens of thousands of e-mails. The hackers picked out phrases and expressions in the e-mails to craft a story that supposedly showed that the scientific facts regarding the alarming rate of global warming[15] and our hand in it were falsified.

The contrived story focused on two leading climate scientists: Phil Jones,[17] head of the research unit, and Michael Mann,[18] director of Pennsylvania State University’s Earth System Science Center, who studies ancient tree ring patterns for climatic conditions. The story suggested that the two researchers deliberately manipulated data to make global warming statistics look more extreme than they actually were.

On Feb. 3, 2010, Michael Mann became the focus of an academic investigation.[20] It concluded “there exists no credible evidence that Dr. Mann had or has ever engaged in, or participated in, directly or indirectly, any actions with an intent to suppress or to falsify data.” Regarding Jones, the results[21] of a British House of Commons Science and Technology Committee investigation stated: “We are content that … colloquial terms used in private e-mails … were not part of a systematic attempt to mislead. Likewise the evidence that we have seen does not suggest that Professor Jones was trying to subvert the peer-review process.”

The American public turns skeptical

As often happens with allegations that later prove wrongful, the outcome didn’t matter. Walter Russell Mead[22] of the Council on Foreign Relations,[23] a New York-based think tank, says events such as Climategate may be causing “the death of the global warming movement as we know it.” In a May 2010 national poll of 1,000 likely voters by Rasmussen Reports,[24] just 40 percent of respondents said they believed human activity was primarily responsible for global warming, down from 47 percent in April 2008.

This year the states of Texas and Virginia, among other entities, filed legal challenges[25] to stop the federal government from regulating emissions of the greenhouse gas carbon dioxide. Lately, even President Obama has been modifying his language: In his State of the Union Address[26] in January, the president called for Congress to support climate change legislation for job-creation purposes “even if you doubt the evidence.”

Senate Democrats, including John Kerry of Massachusetts, have set aside legislation that would limit greenhouse gas emissions[27] from U.S. factories and other businesses. They are pursuing a new bill that may instead focus on utility companies. And State Department Special Envoy on Climate Change Todd Stern[28] said recently that the nation might now pursue a more narrow strategy.

Sen. James Inhofe’s (R.-Okla.) website[29] currently lists more than 700 scientists who agree that the Earth is warming but argue that other factors, such as ocean temperatures or solar flares, play a bigger role than human activity. And Leighton Steward,[30] a geologist and global warming skeptic, allegedly said “we’ve all been kind of giggling as we watch this thing fall apart.”

Not much to laugh about

Admittedly, some mistakes have been made in reporting global warming statistics. For example, one United Nations Intergovernmental Panel on Climate Change[31] (IPCC) report stated that global warming could cause glaciers in the Himalayas to melt by 2035. Later, the IPCC admitted the date was incorrect; the information had been improperly taken from a report issued by an outside environmental group and not subjected to the usual standards of vigorous scientific scrutiny.

But despite such errors, Mann says the core argument — that the Earth is warming, humans are at least partly responsible, and action must be taken to avoid disaster — remains intact. He’s exasperated by the way some politicians use last winter’s East Coast snowstorms as a way to undermine the case for global warming[33] while ignoring a recent NASA announcement that the previous decade was the warmest on record.[34] And Carol Browner,[35] the White House director on climate and energy policy, says there are thousands of scientists whose work provides evidence of global warming from human activities.

Have recent events made you skeptical that our actions on Earth are a major contributor to global warming?

Mann believes there’s a good chance that 2010 will be the hottest year ever. I have to say that judging by my Arkansas-like summer in southern Wisconsin, I do, too.

[3] the hottest on record: http://www.msnbc.msn.com/id/38263788/ns/us_news-environment

[4] Climate Change: Are We on the Brink of a Pronounced Global Warming?: http://www.sciencemag.org/cgi/content/abstract/sci;189/4201/460?maxtoshow=&hits=10&RESULTFORMAT=&fulltext=%28Climatic+AND+Change+AND+Are+AND+We+AND+on+AND+the+AND+Brink+AND+of+AND+a+AND+Pronounced+AND+Global+AND+Warming%29&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT

[19] The Copenhagen conference failed to develop a strong and binding international treaty.: http://www.heritage.org/research/reports/2010/01/the-copenhagen-conference-a-setback-for-bad-climate-policy-in-2010